Fuel injection and mixing systems having piezoelectric elements and methods of using the same

Abstract

A fuel injection and mixing system is provided that is suitable for use with various types of fuel reformers. Preferably, the system includes a piezoelectric injector for delivering atomized fuel, a gas swirler, such as a steam swirler and/or an air swirler, a mixing chamber and a flow mixing device. The system utilizes ultrasonic vibrations to achieve fuel atomization. The fuel injection and mixing system can be used with a variety of fuel reformers and fuel cells, such as SOFC fuel cells.

1. A fuel injector comprising:
 an injector housing; 
 a piezoelectric atomizer body mounted in the injector housing and disposed along a central axis of the injector housing, the atomizer body having a narrowed stem portion with a broadened atomizing tip; 
 a fuel flow passage formed within the injector housing; 
 a fuel jet in fluid communication with the fuel flow passage; 
 a plurality of gas flow passages formed within the injector housing, the plurality of gas flow passages comprising at least an outer gas flow passage and an inner gas flow passage, the outer gas flow passage being farther away from the central axis than the inner gas flow passage; 
 an outer swirler in fluid communication with the outer gas flow passage, the outer swirler having an angled vane configured to direct the gas exiting the outer gas flow passage toward the atomizing face; and 
 an ultrasonic transducer in mechanical communication with the atomizer body, the ultrasonic transducer being configured to cause the atomizer body to resonate at a resonant frequency to atomize the fuel; 
 wherein the fuel jet and the swirler are positioned such that gases exiting the swirler mix with fuel exiting the fuel jet; and 
 wherein the gases direct the fuel toward an atomizing surface of the broadened atomizing tip where atomization of the fuel occurs. 
 
     
     
       2. The fuel injector of  claim 1 , wherein the gases include air and steam. 
     
     
       3. The fuel injector of  claim 1 , wherein the plurality of gas flow passages are each configured to accommodate the flow of at least one of air and steam. 
     
     
       4. The fuel injector of  claim 1 , wherein the inner gas flow passage is in fluid communication with an inner swirler having a plurality of discrete holes circumferentially spaced around the injector housing and positioned such that the gas exiting the inner flow passage is directed toward the atomizing face. 
     
     
       5. The fuel injector of  claim 1 , wherein the outer swirler comprises a plurality of swirlers uniformly distributed around a perimeter of the atomizing surface. 
     
     
       6. The fuel injector of  claim 1 , wherein the fuel jet comprises a plurality of fuel jets equally spaced around a perimeter of the atomizing surface. 
     
     
       7. The fuel injector of  claim 1 , wherein the fuel jet comprises eight fuel jets equally spaced around a perimeter of the atomizing surface. 
     
     
       8. The fuel injector of  claim 1 , wherein the piezoelectric atomizer body is physically isolated from all other portions of the fuel injector. 
     
     
       9. The fuel injector of  claim 1 , further comprising a dampening gasket material interposed between the piezoelectric atomizer body and the injector housing to physically isolate the piezoelectric atomizer from the injector housing. 
     
     
       10. The fuel injector of  claim 1 , further comprising a plurality of O-rings configured to physically isolate the piezoelectric atomizer from the injector housing and to provide a fluid seal. 
     
     
       11. The fuel injector of  claim 1 , wherein the fuel injector is configured to atomize fuel at a mass flow rate of less than about fifteen pounds per hour. 
     
     
       12. A fuel injector comprising:
 an injector housing; 
 a piezoelectric atomizer body mounted in the injector housing, the atomizer body having a narrowed stem portion with a broadened atomizing tip; 
 a fuel flow passage formed within the injector housing; 
 a fuel jet in fluid communication with the fuel flow passage; 
 a gas flow passage formed within the injector housing; 
 a swirler in fluid communication with the gas flow passage; and 
 an ultrasonic transducer in mechanical communication with the atomizer body, the ultrasonic transducer being configured to cause the atomizer body to resonate at a resonant frequency to atomize the fuel; 
 an ultrasonic driver operably coupled to the ultrasonic transducer, wherein the ultrasonic driver is equipped with a frequency sweeping control function to modulate vibrational frequency of an applied pressure wave to optimize atomization; 
 wherein the fuel jet and the swirler are positioned such that gases exiting the swirler mix with fuel exiting the fuel jet; and 
 wherein the gases direct the fuel toward an atomizing surface of the broadened atomizing tip where atomization of the fuel occurs. 
 
     
     
       13. A fuel injector comprising:
 an injector housing; 
 a piezoelectric atomizer body mounted in the injector housing, the atomizer body having a narrowed stem portion with a broadened atomizing tip; 
 a fuel flow passage formed within the injector housing; 
 a fuel jet in fluid communication with the fuel flow passage; 
 a gas flow passage formed within the injector housing; 
 a swirler in fluid communication with the gas flow passage; and 
 an ultrasonic transducer in mechanical communication with the atomizer body, the ultrasonic transducer being configured to cause the atomizer body to resonate at a resonant frequency to atomize the fuel; 
 an ultrasonic driver operably coupled to the ultrasonic transducer, wherein the ultrasonic driver is equipped with a pulse control function to modulate vibrational amplitude of an applied pressure wave to optimize atomization; 
 wherein the fuel jet and the swirler are positioned such that gases exiting the swirler mix with fuel exiting the fuel jet; and 
 wherein the gases direct the fuel toward an atomizing surface of the broadened atomizing tip where atomization of the fuel occurs. 
 
     
     
       14. A fuel injector comprising:
 an injector housing; 
 a piezoelectric atomizer body mounted in the injector housing, the atomizer body having a narrowed stem portion with a broadened atomizing tip; 
 a fuel flow passage formed within the injector housing; 
 a fuel jet in fluid communication with the fuel flow passage; 
 a gas flow passage formed within the injector housing; 
 a swirler in fluid communication with the gas flow passage; and 
 an ultrasonic transducer in mechanical communication with the atomizer body, the ultrasonic transducer being configured to cause the atomizer body to resonate at a resonant frequency to atomize the fuel; 
 an ultrasonic driver operably coupled to the ultrasonic transducer, wherein the ultrasonic driver is equipped with a phase tracking function to monitor and adjust frequency of an applied pressure wave to optimize atomization; 
 wherein the fuel jet and the swirler are positioned such that gases exiting the swirler mix with fuel exiting the fuel jet; and 
 wherein the gases direct the fuel toward an atomizing surface of the broadened atomizing tip where atomization of the fuel occurs.